в чем ошибка?

#include <iostream.h>
 
main()
{
int a, b;
cout << "vvedite 2 chisla";
cin >> a >> b;
cout << "summa ravna =" <<  a + b;
Cout << "proizvedenie ravno =" << a * b;
Cout << "raznost ravna =" << a – b;
Cout << "chastnoe ravno =" a / b;
return 0;
}

#include <iostream>
 
int main(){
int a, b;
cout << “vvedite 2 chisla”;
cin >> a >> b;
cout << “ summa ravna =” <<  a + b;
cout << “ proizvedenie ravno =” << a * b;
cout << “raznost ravna =” << a – b;
cout << “chastnoe ravno =” a / b;
return 0;
}

#include <iostream>
using namespace std;
 
int main()
{
int a, b;
cout << "vvedite 2 chisla";
cin >> a >> b;
cout << "summa ravna =" <<  a + b;
cout << "proizvedenie ravno =" << a * b;
cout << "raznost ravna =" << a - b;
cout << "chastnoe ravno =" << a / b;
return 0;
}

std::cout
std::cin

#include "stdafx.h"
#include <iostream>
using namespace std;
 
int main()
{
int a, b;
cout << "vvedite 2 chisla";
cin >> a >> b;
cout << "summa ravna =" <<  a + b;
cout << "proizvedenie ravno =" << a * b;
cout << "raznost ravna =" << a - b;
cout << "chastnoe ravno =" << a / b;
return 0;
}